--- a/dom/media/NextFrameSeekTask.cpp
+++ b/dom/media/NextFrameSeekTask.cpp
@@ -347,18 +347,16 @@ NextFrameSeekTask::OnVideoNotDecoded(Med
     // delegate the decode error to the generic error path.
     RejectIfExist(__func__);
     return;
   }
 
   // If the decoder is waiting for data, we tell it to call us back when the
   // data arrives.
   if (aReason == MediaDecoderReader::WAITING_FOR_DATA) {
-    MOZ_ASSERT(mReader->IsWaitForDataSupported(),
-               "Readers that send WAITING_FOR_DATA need to implement WaitForData");
     mReader->WaitForData(MediaData::VIDEO_DATA);
 
     // We are out of data to decode and will enter buffering mode soon.
     // We want to play the frames we have already decoded, so we stop pre-rolling
     // and ensure that loadeddata is fired as required.
     mNeedToStopPrerollingVideo = true;
     return;
   }